A typical DRM licensing system uses tokens to protect distributed electronic content. The token contains the information pertaining to the at least the rights the user is allowed to exercise regarding the content. Typically, a token is generated and passed to the user device rendering the electronic content. In a subscription based licensing system, the token is renewed periodically to allow the user continued access to the electronic content. When the user's subscription lapse, the token is not renewed and the user is denied access to the electronic content.
The benefit of a subscription based DRM system is that the user can have unlimited access to some or all of a provider's catalogue of electronic content for a fixed subscription rate. Typically, the user can only receive the subscription based content on a fixed number of devices. For example, the user can only use three different desktops and/or handheld players (e.g. MP3 players). Prior art DRM systems receive a request from a user to access content on a first device, the DRM system passes the token to the first device and increments a counter (either reduced from the fixed number or counts up from zero) and the first device is now an authorized device. When the user requests a download to a subsequent device, the token is passed and the counter is likewise incremented until the maximum number of authorized devices is reached. Once the maximum number is reached, any further requests for access by a user are denied. The user can continuously request and be granted access to electronic content on any authorized device because the DRM system checks for the presence of the token, and once confirmed, allows access to the requested electronic content.
However, the prior art DRM system does not track the authorized devices. The system only tracks the number of requests and the presence of tokens. This causes a problem when the token on the authorized device is erased. Typically, the token is hidden and transparent to the user to avoid tampering and/or erasure by the user. However, if the user reformats the memory on the authorized device, the token is erased. After formatting, when the user requests access to the content, the prior art DRM system checks the authorized device for a token and determines that one is not present and thus does not consider it an authorized device. The system then looks to the counter and determines that the user has, in this example, reached the maximum number of authorized devices, and does not allow access to the content. However, access to the content should be allowed because this is not an additional device, but an authorized device. The user then must request assistance to fix the problem. This is frustrating to a user, especially if the same authorized device is continuously reformatted, which is a frequent occurrence with some handheld devices, and then “re-licensed” until the maximum number of authorized devices is reached.
Thus, it is an object of the present invention to allow users access to content on their authorized devices even if the authorizing token is erased. Further, it is an object of the invention to allow the access to the authorized devices and still maintain the limit of the maximum number of devices.